Brain Power: Grades 4-5

Background

Module 2 provides the students with important information about the structure of the brain. They will refer to this information later in the program, when learning about the effects that drugs have on different parts of the brain.

In the Brain Power! program for the students in grades 2 and 3, they learned about four parts of the brain—the cerebral cortex, composed of the right and left hemispheres; the cerebellum; the brain stem; and the limbic system. In this program, they will learn more detail about the different functions localized in each area. If they haven’t already completed the second- and third-grade curriculum, review the basics about the brain in more detail.

Cerebral cortex: right and left hemispheres

In people, the cerebral cortex is the brain’s largest part, making up more than 3/4 of the brain. It is considered to be the most highly developed part of the brain and controls thinking, perceiving, and understanding language.

The cerebral cortex is divided into two hemispheres—the right hemisphere and the left hemisphere. The right hemisphere controls the left side of the body and is largely responsible for artistic expression and understanding relationships in space.

The left hemisphere, which controls the right side of the body, is largely responsible for mathematical ability, problem solving, and comparing information needed to make decisions. It is also the brain’s center of language.

The two hemispheres can communicate with one another because of a bundle of fibers called the corpus callosum. The corpus callosum serves as the bridge between the two hemispheres.

The cortex is specialized—specific areas of the cortex, called lobes, are responsible for different tasks, such as the following:

The frontal lobe is responsible for initiating and coordinating motor movements and higher cognitive skills like problem solving and thinking.

The job of the parietal lobe is to process sensory information from the whole body—like information about pain, touch, and pressure.

The occipital lobe processes all the visual information coming into the brain.

The temporal lobe is in charge of making sense of the auditory information from the environment. It is also involved in integrating sensory information from various senses, such as smell and vision.

Cerebellum

The cerebellum controls posture, movement, and the sense of balance. Playing ball, picking up objects, and playing musical instruments are just a few of the activities that fall under its control.

Brain Stem

The brain stem is the brain’s most primitive part. Its two main parts are the pons and the medulla. The pons contains fibers that connect the cerebral cortex with the cerebellum and the spinal cord. The pons also controls sleeping, awakening, and dreaming.

The medulla controls heart rate, respiration, and blood pressure. The brain stem also controls simple reflexes, such as coughing, sneezing, and digestion.

Limbic System

The limbic system has many parts, but two of the most important are the hippocampus and the amygdala. The hippocampus is mainly responsible for learning and memory. The amygdala plays an important role in emotional behavior. The limbic system is greatly affected by drugs such as nicotine, alcohol, and illegal drugs.

New Tools for Studying the Brain

Scientists now have very sophisticated techniques for studying the brain. Three important tools that are used are PET, SPECT, and MRI. Each of these tools is described below.

Positron Emission Tomography (PET) scans. Radioactive glucose is injected into the bloodstream; the radioactive glucose is then taken up by parts of the brain that are active and using energy. These areas, which are using either radioactive oxygen or glucose, show up on the image. The advantage of this technique is that it can actually show what parts of the brain are more active than others. The disadvantages are that it is expensive to use and involves radioactive material, which has the potential to be dangerous.

Single-Photon Emission Computed Tomography (SPECT) scans. Similar to PET scans, radioactive material is injected into the bloodstream and travels to the brain and body. Scientists and doctors can view the material on computerized images, which helps them identify brain activity. The radioactive substances used in SPECT are different from those used in PET scans, and the SPECT images are less detailed than those of PET. On the other hand, SPECT is less expensive than PET, and SPECT centers are more accessible than PET centers because they have fewer equipment requirements.

Magnetic Resonance Imaging (MRI). MRI uses radio frequency signals produced in a strong magnetic field to create an image of the brain and show what it looks like. MRIs show the structure of the entire brain, as opposed to the other types of imaging, which show the specific parts that are working. While MRIs produce clear images, they are expensive to use and can be uncomfortable for the patient, who must lie still in a very small space for a relatively long period of time. However, a big advantage is that MRI is noninvasive and doesn’t use injections or radioactivity.

During the activity, the students will have an opportunity to look at images produced from these three different tools to see what each shows and how the images can be used to learn more about the brain.